Liquid crystal displays (LCDs) contains a plurality of picture elements, or pixels, formed by liquid crystal cells that change the polarization direction of light in response to an electrical voltage. By controlling a voltage applied to a liquid crystal cell, the intensity of light coming out of the LCDs changes. Among various driving methods, active matrix liquid crystal displays, which have a switching element such as a thin film transistor for each of the pixels so as to control a voltage to be applied to the liquid crystal, are superior in display quality and have been intensively developed and come to be widely used.
In addition to a panel having upper and lower glass substrates with a liquid crystal layer interposed therebetween to control the intensity of light coming out of LCDs, LCDs must first have a backlight unit arranged under the liquid crystal display panel to furnish visible lights. The backlight is traditionally generated by cold cathode fluorescent lamps (CCFLs). A blink backlight using CCFLs has been proposed to improve the display quality of moving pictures.
However, the blinking operation of CCFLs causes more than 10% luminance lost depending on the number of CCFLs employed. In addition, CCFLs have long response time of about 5 ms which becomes an obstacle for improving the display quality of moving pictures. Moreover, it is more difficult to manage the intersection problem caused by overlap of lights emitted from adjacent CCFL tubes. It is also more costly to use CCFLs because each CCFL needs an individual inverter to function normally.